As soon as the browser specs catch up to what the bundlers are doing I’d drop them in a heartbeat. Not holding my breath though
The only thing I'm still missing is an offline JSPM/esm.sh.
Also why not use this config in production? Http2 should give the same performance for multiple small files than a big bundle and it's much better to cache
CSS has advanced enough that I haven't used Less or Sass in many years. Modules make loading easy. Import maps let you use bare module specifiers (or you could use a simple transform in a dev server). CSS modules let you import CSS into JavaScript.
I never use a bundler during development.